The beautiful residue left in a womans panty crotch after long wear and/or arousal. Usually drying to a powdery whitish/yellow color, holding in the scent of her sex as well as making for a great sniffing and licking prospect later while jerking off.
Hey, she was so hot before we banged, I slipped her pantys off and realized it had panty soup. I carefully rolled them up, crotch on the inside and pocketted them. Later they gave me a lot of pleasure, sniffing and licking the crotch while I jerked off on my towel.